Food patties of various kinds, including hamburgers, molded "steaks", fish cakes, chicken patties, pork patties, potato patties, and others, are frequently formed in high-volume automated molding machines. Patty molding machines that can be adapted to any of these food products and that have proven quite successful are described in U.S. Pat. No. 3,887,964 to L. R. Richards, No. 4,054,967 to G. A. Sandberg et al, and No. 4,182,003 to LaMartino et al.
Although any of these machines, and others as well, are capable of producing food patties of consistent size, weight, and configuration on a high volume basis, substantial problems and difficulties still remain in some instances. Thus, in most patty molding machines it is quite difficult to duplicate the texture of hamburgers and other patties that are hand-molded. The machine-molded food patties frequently exhibit a tendency toward excess shrinkage when the patties are subsequently cooked. Another continuing problem pertains to distortion in the shape of the food patties, again occurring primarily when the patties are cooked.
The aforementioned Sandberg et al U.S. patent application Ser. No. 204,840 discloses a method and apparatus for molding food patties that produces patties of essentially uniform texture having minimal shrinkage when the patties are cooked. Furthermore, the patties hold their shape consistently following cooking. In that patty molding machine, in one embodiment, a multi-orifice plate is interposed in the outlet end of a fill passage extending from a food pump to a cyclically moving mold plate. To minimize buildup of food product on the orifice plate, the edges of the orifices facing the food pump are rounded. Furthermore, the operation of the food pump is modified, as compared with prior art practice, so that the maximum fill pressure, required for adequate filling of the mold cavities, is used for only a limited part of each mold plate cycle; the pressure is reduced to an intermediate pressure during a minor fraction of the mold plate cycle immediately following filling of the mold cavities, and then maintained at the intermediate level or reduced even further during the balance of the mold plate cycle, a period of at least about half of the total cycle.
That arrangement, though highly satisfactory for many food products (e.g., ground pork, ground chicken, finely ground beef, etc.) is not entirely successful for other foods, particularly those that may incorporate relatively long and sometimes tough fibrous components. An example of such a food product is ground beef, particularly if the beef is coarsely ground. A food product of this nature still tends to create a buildup of fibrous material at the entrances of the orifices, requiring an excessive increase in the food product pressure in order to maintain operation of the patty molding machine at the desired speed.